net/ethernet/eth.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Ethernet-type device handling.
   7  *
   8  * Version:     @(#)eth.c       1.0.7   05/25/93
   9  *
  10  * Authors:     Ross Biro
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  13  *              Florian  La Roche, <rzsfl@rz.uni-sb.de>
  14  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  15  *
  16  * Fixes:
  17  *              Mr Linux        : Arp problems
  18  *              Alan Cox        : Generic queue tidyup (very tiny here)
  19  *              Alan Cox        : eth_header ntohs should be htons
  20  *              Alan Cox        : eth_rebuild_header missing an htons and
  21  *                                minor other things.
  22  *              Tegge           : Arp bug fixes.
  23  *              Florian         : Removed many unnecessary functions, code cleanup
  24  *                                and changes for new arp and skbuff.
  25  *              Alan Cox        : Redid header building to reflect new format.
  26  *              Alan Cox        : ARP only when compiled with CONFIG_INET
  27  *              Greg Page       : 802.2 and SNAP stuff.
  28  *              Alan Cox        : MAC layer pointers/new format.
  29  *              Paul Gortmaker  : eth_copy_and_sum shouldn't csum padding.
  30  *              Alan Cox        : Protect against forwarding explosions with
  31  *                                older network drivers and IFF_ALLMULTI.
  32  *      Christer Weinigel       : Better rebuild header message.
  33  *             Andrew Morton    : 26Feb01: kill ether_setup() - use netdev_boot_setup().
  34  *
  35  *              This program is free software; you can redistribute it and/or
  36  *              modify it under the terms of the GNU General Public License
  37  *              as published by the Free Software Foundation; either version
  38  *              2 of the License, or (at your option) any later version.
  39  */
  40 #include <linux/module.h>
  41 #include <linux/types.h>
  42 #include <linux/kernel.h>
  43 #include <linux/string.h>
  44 #include <linux/mm.h>
  45 #include <linux/socket.h>
  46 #include <linux/in.h>
  47 #include <linux/inet.h>
  48 #include <linux/ip.h>
  49 #include <linux/netdevice.h>
  50 #include <linux/etherdevice.h>
  51 #include <linux/skbuff.h>
  52 #include <linux/errno.h>
  53 #include <linux/init.h>
  54 #include <linux/if_ether.h>
  55 #include <net/dst.h>
  56 #include <net/arp.h>
  57 #include <net/sock.h>
  58 #include <net/ipv6.h>
  59 #include <net/ip.h>
  60 #include <net/dsa.h>
  61 #include <asm/uaccess.h>
  62 #include <asm/system.h>
  63
  64 __setup("ether=", netdev_boot_setup);
  65
  66 /**
  67  * eth_header - create the Ethernet header
  68  * @skb:        buffer to alter
  69  * @dev:        source device
  70  * @type:       Ethernet type field
  71  * @daddr: destination address (NULL leave destination address)
  72  * @saddr: source address (NULL use device source address)
  73  * @len:   packet length (<= skb->len)
  74  *
  75  *
  76  * Set the protocol type. For a packet of type ETH_P_802_3 we put the length
  77  * in here instead. It is up to the 802.2 layer to carry protocol information.
  78  */
  79 int eth_header(struct sk_buff *skb, struct net_device *dev,
  80                unsigned short type,
  81                const void *daddr, const void *saddr, unsigned len)
  82 {
  83         struct ethhdr *eth = (struct ethhdr *)skb_push(skb, ETH_HLEN);
  84
  85         if (type != ETH_P_802_3)
  86                 eth->h_proto = htons(type);
  87         else
  88                 eth->h_proto = htons(len);
  89
  90         /*
  91          *      Set the source hardware address.
  92          */
  93
  94         if (!saddr)
  95                 saddr = dev->dev_addr;
  96         memcpy(eth->h_source, saddr, ETH_ALEN);
  97
  98         if (daddr) {
  99                 memcpy(eth->h_dest, daddr, ETH_ALEN);
 100                 return ETH_HLEN;
 101         }
 102
 103         /*
 104          *      Anyway, the loopback-device should never use this function...
 105          */
 106
 107         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 108                 memset(eth->h_dest, 0, ETH_ALEN);
 109                 return ETH_HLEN;
 110         }
 111
 112         return -ETH_HLEN;
 113 }
 114 EXPORT_SYMBOL(eth_header);
 115
 116 /**
 117  * eth_rebuild_header- rebuild the Ethernet MAC header.
 118  * @skb: socket buffer to update
 119  *
 120  * This is called after an ARP or IPV6 ndisc it's resolution on this
 121  * sk_buff. We now let protocol (ARP) fill in the other fields.
 122  *
 123  * This routine CANNOT use cached dst->neigh!
 124  * Really, it is used only when dst->neigh is wrong.
 125  */
 126 int eth_rebuild_header(struct sk_buff *skb)
 127 {
 128         struct ethhdr *eth = (struct ethhdr *)skb->data;
 129         struct net_device *dev = skb->dev;
 130
 131         switch (eth->h_proto) {
 132 #ifdef CONFIG_INET
 133         case htons(ETH_P_IP):
 134                 return arp_find(eth->h_dest, skb);
 135 #endif
 136         default:
 137                 printk(KERN_DEBUG
 138                        "%s: unable to resolve type %X addresses.\n",
 139                        dev->name, (int)eth->h_proto);
 140
 141                 memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 142                 break;
 143         }
 144
 145         return 0;
 146 }
 147 EXPORT_SYMBOL(eth_rebuild_header);
 148
 149 /**
 150  * eth_type_trans - determine the packet's protocol ID.
 151  * @skb: received socket data
 152  * @dev: receiving network device
 153  *
 154  * The rule here is that we
 155  * assume 802.3 if the type field is short enough to be a length.
 156  * This is normal practice and works for any 'now in use' protocol.
 157  */
 158 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 159 {
 160         struct ethhdr *eth;
 161         unsigned char *rawp;
 162
 163         skb->dev = dev;
 164         skb_reset_mac_header(skb);
 165         skb_pull(skb, ETH_HLEN);
 166         eth = eth_hdr(skb);
 167
 168         if (unlikely(is_multicast_ether_addr(eth->h_dest))) {
 169                 if (!compare_ether_addr_64bits(eth->h_dest, dev->broadcast))
 170                         skb->pkt_type = PACKET_BROADCAST;
 171                 else
 172                         skb->pkt_type = PACKET_MULTICAST;
 173         }
 174
 175         /*
 176          *      This ALLMULTI check should be redundant by 1.4
 177          *      so don't forget to remove it.
 178          *
 179          *      Seems, you forgot to remove it. All silly devices
 180          *      seems to set IFF_PROMISC.
 181          */
 182
 183         else if (1 /*dev->flags&IFF_PROMISC */ ) {
 184                 if (unlikely(compare_ether_addr_64bits(eth->h_dest, dev->dev_addr)))
 185                         skb->pkt_type = PACKET_OTHERHOST;
 186         }
 187
 188         /*
 189          * Some variants of DSA tagging don't have an ethertype field
 190          * at all, so we check here whether one of those tagging
 191          * variants has been configured on the receiving interface,
 192          * and if so, set skb->protocol without looking at the packet.
 193          */
 194         if (netdev_uses_dsa_tags(dev))
 195                 return htons(ETH_P_DSA);
 196         if (netdev_uses_trailer_tags(dev))
 197                 return htons(ETH_P_TRAILER);
 198
 199         if (ntohs(eth->h_proto) >= 1536)
 200                 return eth->h_proto;
 201
 202         rawp = skb->data;
 203
 204         /*
 205          *      This is a magic hack to spot IPX packets. Older Novell breaks
 206          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 207          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 208          *      won't work for fault tolerant netware but does for the rest.
 209          */
 210         if (*(unsigned short *)rawp == 0xFFFF)
 211                 return htons(ETH_P_802_3);
 212
 213         /*
 214          *      Real 802.2 LLC
 215          */
 216         return htons(ETH_P_802_2);
 217 }
 218 EXPORT_SYMBOL(eth_type_trans);
 219
 220 /**
 221  * eth_header_parse - extract hardware address from packet
 222  * @skb: packet to extract header from
 223  * @haddr: destination buffer
 224  */
 225 int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 226 {
 227         const struct ethhdr *eth = eth_hdr(skb);
 228         memcpy(haddr, eth->h_source, ETH_ALEN);
 229         return ETH_ALEN;
 230 }
 231 EXPORT_SYMBOL(eth_header_parse);
 232
 233 /**
 234  * eth_header_cache - fill cache entry from neighbour
 235  * @neigh: source neighbour
 236  * @hh: destination cache entry
 237  * Create an Ethernet header template from the neighbour.
 238  */
 239 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh)
 240 {
 241         __be16 type = hh->hh_type;
 242         struct ethhdr *eth;
 243         const struct net_device *dev = neigh->dev;
 244
 245         eth = (struct ethhdr *)
 246             (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 247
 248         if (type == htons(ETH_P_802_3))
 249                 return -1;
 250
 251         eth->h_proto = type;
 252         memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 253         memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
 254         hh->hh_len = ETH_HLEN;
 255         return 0;
 256 }
 257 EXPORT_SYMBOL(eth_header_cache);
 258
 259 /**
 260  * eth_header_cache_update - update cache entry
 261  * @hh: destination cache entry
 262  * @dev: network device
 263  * @haddr: new hardware address
 264  *
 265  * Called by Address Resolution module to notify changes in address.
 266  */
 267 void eth_header_cache_update(struct hh_cache *hh,
 268                              const struct net_device *dev,
 269                              const unsigned char *haddr)
 270 {
 271         memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 272                haddr, ETH_ALEN);
 273 }
 274 EXPORT_SYMBOL(eth_header_cache_update);
 275
 276 /**
 277  * eth_mac_addr - set new Ethernet hardware address
 278  * @dev: network device
 279  * @p: socket address
 280  * Change hardware address of device.
 281  *
 282  * This doesn't change hardware matching, so needs to be overridden
 283  * for most real devices.
 284  */
 285 int eth_mac_addr(struct net_device *dev, void *p)
 286 {
 287         struct sockaddr *addr = p;
 288
 289         if (netif_running(dev))
 290                 return -EBUSY;
 291         if (!is_valid_ether_addr(addr->sa_data))
 292                 return -EADDRNOTAVAIL;
 293         memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
 294         return 0;
 295 }
 296 EXPORT_SYMBOL(eth_mac_addr);
 297
 298 /**
 299  * eth_change_mtu - set new MTU size
 300  * @dev: network device
 301  * @new_mtu: new Maximum Transfer Unit
 302  *
 303  * Allow changing MTU size. Needs to be overridden for devices
 304  * supporting jumbo frames.
 305  */
 306 int eth_change_mtu(struct net_device *dev, int new_mtu)
 307 {
 308         if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
 309                 return -EINVAL;
 310         dev->mtu = new_mtu;
 311         return 0;
 312 }
 313 EXPORT_SYMBOL(eth_change_mtu);
 314
 315 int eth_validate_addr(struct net_device *dev)
 316 {
 317         if (!is_valid_ether_addr(dev->dev_addr))
 318                 return -EADDRNOTAVAIL;
 319
 320         return 0;
 321 }
 322 EXPORT_SYMBOL(eth_validate_addr);
 323
 324 const struct header_ops eth_header_ops ____cacheline_aligned = {
 325         .create         = eth_header,
 326         .parse          = eth_header_parse,
 327         .rebuild        = eth_rebuild_header,
 328         .cache          = eth_header_cache,
 329         .cache_update   = eth_header_cache_update,
 330 };
 331
 332 /**
 333  * ether_setup - setup Ethernet network device
 334  * @dev: network device
 335  * Fill in the fields of the device structure with Ethernet-generic values.
 336  */
 337 void ether_setup(struct net_device *dev)
 338 {
 339         dev->header_ops         = &eth_header_ops;
 340         dev->type               = ARPHRD_ETHER;
 341         dev->hard_header_len    = ETH_HLEN;
 342         dev->mtu                = ETH_DATA_LEN;
 343         dev->addr_len           = ETH_ALEN;
 344         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 345         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 346
 347         memset(dev->broadcast, 0xFF, ETH_ALEN);
 348
 349 }
 350 EXPORT_SYMBOL(ether_setup);
 351
 352 /**
 353  * alloc_etherdev_mq - Allocates and sets up an Ethernet device
 354  * @sizeof_priv: Size of additional driver-private structure to be allocated
 355  *      for this Ethernet device
 356  * @queue_count: The number of queues this device has.
 357  *
 358  * Fill in the fields of the device structure with Ethernet-generic
 359  * values. Basically does everything except registering the device.
 360  *
 361  * Constructs a new net device, complete with a private data area of
 362  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
 363  * this private data area.
 364  */
 365
 366 struct net_device *alloc_etherdev_mq(int sizeof_priv, unsigned int queue_count)
 367 {
 368         return alloc_netdev_mq(sizeof_priv, "eth%d", ether_setup, queue_count);
 369 }
 370 EXPORT_SYMBOL(alloc_etherdev_mq);
 371
 372 static size_t _format_mac_addr(char *buf, int buflen,
 373                                 const unsigned char *addr, int len)
 374 {
 375         int i;
 376         char *cp = buf;
 377
 378         for (i = 0; i < len; i++) {
 379                 cp += scnprintf(cp, buflen - (cp - buf), "%02x", addr[i]);
 380                 if (i == len - 1)
 381                         break;
 382                 cp += strlcpy(cp, ":", buflen - (cp - buf));
 383         }
 384         return cp - buf;
 385 }
 386
 387 ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
 388 {
 389         size_t l;
 390
 391         l = _format_mac_addr(buf, PAGE_SIZE, addr, len);
 392         l += strlcpy(buf + l, "\n", PAGE_SIZE - l);
 393         return ((ssize_t) l);
 394 }
 395 EXPORT_SYMBOL(sysfs_format_mac);
 396
 397 char *print_mac(char *buf, const unsigned char *addr)
 398 {
 399         _format_mac_addr(buf, MAC_BUF_SIZE, addr, ETH_ALEN);
 400         return buf;
 401 }
 402 EXPORT_SYMBOL(print_mac);